Question 909285
Let {{{ x }}} = amount invested at 11% simple interest
The total interest earned is:
{{{ .07*2500 + .11x }}}
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given:
{{{ .07*2500 + .11x = .09*( 2500 + x ) }}}
{{{ 175 + .11x = 225 + .09x }}}
{{{ .02x = 50 }}}
{{{ x = 2500 }}}
The amount invested at 11% 
simple interest is $2,500
check:
{{{ .07*2500 + .11*2500 = .09*( 2500 + 2500 ) }}}
{{{ 175 + 275 = .09*5000 }}}
{{{ 450 = 450 }}}
OK